1. Field of the Invention
The present invention relates to a combination weighing apparatus having a plurality of hoppers arranged in a rectilinear row.
2. Description of the Prior Art
The combination weighing apparatus is known which is operable to a combine articles together after the articles have been weighed by a plurality of weighing hoppers. Where the articles difficult to be automatically delivered due to the shape and/or nature of the articles, a so-called in-line combination weighing apparatus wherein the weighing hoppers are arranged in a rectilinear row is generally utilized to facilitate a manual delivery of the articles. Also, since the in-line combination weighing apparatus is effective in that the articles are weighed and delivered as supplied in an aligned fashion, it is generally used for weighing elongated articles. The manual delivery operation performed with the in-line combination weighing apparatus includes delivery of the articles onto empty weighing hoppers after an operator watching the articles being handled has determined such weighing hoppers having been emptied. On the other hand, automatic delivery includes transportation of the articles by means of a belt conveyor and vibrating the belt conveyor so that the articles can be dispensed onto the weighing hoppers from a downstream end of the belt conveyor. See, for example, the Japanese Laid-open Patent Publication No. 59-36031.
However, manual delivery of the articles onto some of the weighing hoppers which the operator determine with his or her naked eyes that they are emptied requires the operator to look around a number of sites and, therefore, not only is an error in delivery likely to occur, but high speed automation is difficult to achieve.
On the other hand, with the prior art in which automated delivery is performed using the belt conveyor as hereinbefore discussed, the shape of the articles that can be supplied is limited. By way of example, where the articles are elongated in shape such as, for example, scallions or burdocks, the articles cannot be generally delivered onto the weighing hoppers in an aligned fashion with ease and, for this reason, the articles cannot be discharged in an aligned fashion.
Also, with the prior art in which automated delivery is performed, since the belt conveyor is vibrated in a horizontal place to allow the articles to be successively delivered downwardly from the downward end of the belt conveyor, delivery pitch can hardly be speeded up, resulting in inefficient utilization of the handling capacity of the combination weighing apparatus.
Accordingly, an important object of the present invention is to provide an improved combination weighing apparatus which is versatile enough to handle articles of various shapes and which can be automated to operate at a high speed.
In order to accomplish the foregoing object of the present invention, the present invention in accordance with one aspect thereof provides a combination weighing apparatus for weighing articles supplied to a plurality of hoppers, arranged in a rectilinear row, from a supply unit, combining some of the hoppers and grouping together the articles within selected ones of the hoppers. The supply unit includes a plurality of supply buckets each capable of accommodating an article therein and discharging it onto the hoppers; transport means including an endless support member for drivingly supporting the supply buckets and operable to circulate the supply buckets along a predetermined path together with the support member past a discharge position above the row of the hoppers; determining means for determining, in reference to a weight of the article within each of the hoppers, whether or not the respective hopper is ready to receive the article; and discharge control means for, when the supply buckets are successively brought to a position corresponding to some of the hoppers ready to receive the articles therefrom, causing the supply buckets to discharge the corresponding articles onto such some of the hoppers.
According to the present invention, an operator of the combination weighing apparatus delivers articles onto the supply buckets being circulated along the transport path. On the other hand, the articles within the supply buckets being circulated are successively supplied onto the weighing hoppers. Accordingly, the operator need not deliver the articles directly onto the weighing hoppers.
More specifically, since a bucket conveyor is employed so as to extend along the rectilinear row of the weighing hoppers so that the articles can be discharged by the effect of a gravitational force onto the weighing hoppers from the supply buckets being circulated, the articles can be quickly supplied from the plural supply buckets onto the weighing hoppers. Accordingly, a high speed feature, i.e., reduction of the supply cycle can be achieved. Also, if the shape of each of the supply buckets is tailored to represent a shape similar to that of the articles being handled, the combination weighing apparatus of the present invention can handle the elongated articles. Also, since the supply buckets are circulated along the transport path, the position at which the articles are successively delivered onto the supply buckets can advantageously be fixed at a predetermined site, the operator need not look around which would otherwise be required if manual delivery is performed as hereinbefore discussed, eliminating the possible error in delivery of the articles and also allowing a separate supply device to be used for automatic delivery.
In one preferred embodiment of the present invention the determining means may be operable to determine that, when some of the hoppers are empty, such some of the hoppers are ready to receive the articles therein, but when some of the hoppers are not empty, such some of the hoppers are incapable of receiving the articles therein.
In another preferred embodiment of the present invention, the discharge control means may be operable to cause the supply buckets to undergo a discharge operation when the supply buckets, regardless of whether or not they contain articles therein, are successively brought to the position corresponding to some of the hoppers not containing the articles therein, but to cause the supply buckets to undergo no discharge operation when the supply buckets are successively brought to a position corresponding to some of the hoppers containing the articles therein.
In either case, neither detection of whether or not the supply buckets contain articles therein nor a tracking control is needed and, accordingly, the control can be easily and simply performed.
In a further preferred embodiment of the present invention, the combination weighing apparatus of the present invention may further include a weight detector for detecting a weight of each of the hoppers onto which the article is to be discharged from the supply unit.
The determining means when receiving an output from the weight detector may preferably determine whether or not the weight of the article within the respective hopper is not greater than a predetermined threshold value, and wherein the discharge control means operates, when the supply buckets are successively brought to a position corresponding to some of the hoppers containing the respective articles of the weight not greater than the predetermined threshold value, to cause the supply buckets to discharge the corresponding articles onto such some of the hoppers.
Where the weight detector is employed, it is possible to reduce the number of the supply buckets which move idle without the articles delivered thereonto and, accordingly, the workability of the combination weighing apparatus can advantageously be increased.
Preferably, the predetermined threshold value is a value equal to a combination target value less a standard weight for a predetermined discharge unit.
In one embodiment of the present invention, the discharge control means may cause the supply buckets, regardless of whether or not they contain the articles therein, to undergo the discharge operation when the supply buckets are successively transported to a position corresponding to empty hoppers, and also may cause some of the supply buckets, when the latter contain the article of the weight not greater than the predetermined threshold value, to undergo the discharge operation to discharge the articles therefrom onto such hoppers.
Also, the discharge control means is preferably employed for each of the hoppers.
In a further preferred embodiment of the present invention, the supply buckets are preferably spaced from each other at intervals of a predetermined first pitch and the hoppers are also spaced from each other at intervals of a predetermined second pitch, wherein the first and second pitches are equal to each other.
Where the pitch between the neighboring supply buckets and the pitch between the neighboring weighing hoppers are equal to each other, the timings at which the articles are discharged from each supply bucket onto the associated weighing hopper by the effect of a gravitational force need not be controlled one another and it is sufficient for some of the supply buckets which have to discharge the articles to undergo the discharge operation simultaneously, the control of the timings can be achieved easily.
Also, each of the supply buckets is preferably formed so as to elongate in a direction perpendicular to a direction of circulation thereof, so that the elongated articles within the selected weighing hoppers can be grouped together by combining some of the weighing hoppers while the elongated articles are aligned with the supply buckets.
The present invention in accordance with another aspect thereof provides a combination weighing system. This system includes the combination weighing apparatus of a type discussed above; a front stage supply device positioned upstream of the combination weighing apparatus with respect to a direction of delivery of articles for delivering the articles successively onto the supply unit; article detecting means for detecting presence or absence of the article in the supply buckets before each of the supply buckets receives the articles from the front stage supply device; and a front stage control means operable on a basis of article detection information from the article detecting means to control supply of the articles from the front stage supply device towards the supply unit.
According to the combination weighing system of the kind described above, the provision of the front stage supply device is effective to eliminate the necessity of an operator to deliver the articles onto the supply buckets, thereby resulting in increase of the workability.
In accordance with a further aspect of the present invention, there is also provided a combination weighing system which includes the combination weighing apparatus of the kind described hereinbefore; a front stage supply device positioned upstream of the combination weighing apparatus with respect to a direction of delivery of articles for delivering the articles successively onto the supply unit; and discharge means for causing the supply buckets to undergo the discharge operation when the supply buckets are brought to a discharge position defined at a location downstream of one of the hoppers that is positioned most downstream of the path of circulation of the supply buckets. The front stage supply device delivers the articles onto the supply buckets which have undergone the discharge operation.
According to the second mentioned combination weighing system, since at a position upstream of the front stage supply device the articles are discharged from the supply buckets so that the supply buckets can be emptied at all times, it is possible to prevent each of the supply buckets from receiving an excessive amount of articles.